
var w = c.width = window.innerWidth,
    h = c.height = window.innerHeight,
    ctx = c.getContext('2d'),
    opts = {
        len: 20,
        count: 50,
        baseTime: 10,
        addedTime: 10,
        dieChance: .05,
        spawnChance: 1,
        sparkChance: .1,
        sparkDist: 10,
        sparkSize: 2,
        color: 'hsl(hue,100%,light%)',
        baseLight: 50,
        addedLight: 10,
        shadowToTimePropMult: 6,
        baseLightInputMultiplier: .01,
        addedLightInputMultiplier: .02,
        cx: w / 2,
        cy: h / 2,
        repaintAlpha: .04,
        hueChange: .1
    },
    tick = 0,
    lines = [],
    dieX = w / 2 / opts.len,
    dieY = h / 2 / opts.len,
    baseRad = Math.PI * 2 / 6;
ctx.fillStyle = 'black';
ctx.fillRect(0, 0, w, h);
function loop() {
    window.requestAnimationFrame(loop); ++tick;
    ctx.globalCompositeOperation = 'source-over';
    ctx.shadowBlur = 0;
    ctx.fillStyle = 'rgba(0,0,0,alp)'.replace('alp', opts.repaintAlpha);
    ctx.fillRect(0, 0, w, h);
    ctx.globalCompositeOperation = 'lighter';
    if (lines.length < opts.count && Math.random() < opts.spawnChance) lines.push(new Line);
    lines.map(function(line) {
        line.step()
    })
}
function Line() {
    this.reset()
}
Line.prototype.reset = function() {
    this.x = 0;
    this.y = 0;
    this.addedX = 0;
    this.addedY = 0;
    this.rad = 0;
    this.lightInputMultiplier = opts.baseLightInputMultiplier + opts.addedLightInputMultiplier * Math.random();
    this.color = opts.color.replace('hue', tick * opts.hueChange);
    this.cumulativeTime = 0;
    this.beginPhase()
}
Line.prototype.beginPhase = function() {
    this.x += this.addedX;
    this.y += this.addedY;
    this.time = 0;
    this.targetTime = (opts.baseTime + opts.addedTime * Math.random()) | 0;
    this.rad += baseRad * (Math.random() < .5 ? 1 : -1);
    this.addedX = Math.cos(this.rad);
    this.addedY = Math.sin(this.rad);
    if (Math.random() < opts.dieChance || this.x > dieX || this.x < -dieX || this.y > dieY || this.y < -dieY) this.reset()
}
Line.prototype.step = function() {++this.time; ++this.cumulativeTime;
    if (this.time >= this.targetTime) this.beginPhase();
    var prop = this.time / this.targetTime,
        wave = Math.sin(prop * Math.PI / 2),
        x = this.addedX * wave,
        y = this.addedY * wave;
    ctx.shadowBlur = prop * opts.shadowToTimePropMult;
    ctx.fillStyle = ctx.shadowColor = this.color.replace('light', opts.baseLight + opts.addedLight * Math.sin(this.cumulativeTime * this.lightInputMultiplier));
    ctx.fillRect(opts.cx + (this.x + x) * opts.len, opts.cy + (this.y + y) * opts.len, 2, 2);
    if (Math.random() < opts.sparkChance) ctx.fillRect(opts.cx + (this.x + x) * opts.len + Math.random() * opts.sparkDist * (Math.random() < .5 ? 1 : -1) - opts.sparkSize / 2, opts.cy + (this.y + y) * opts.len + Math.random() * opts.sparkDist * (Math.random() < .5 ? 1 : -1) - opts.sparkSize / 2, opts.sparkSize, opts.sparkSize)
}
loop();
window.addEventListener('resize',
    function() {
        w = c.width = window.innerWidth;
        h = c.height = window.innerHeight;
        ctx.fillStyle = 'black';
        ctx.fillRect(0, 0, w, h);
        opts.cx = w / 2;
        opts.cy = h / 2;
        dieX = w / 2 / opts.len;
        dieY = h / 2 / opts.len
    });
    